WEFT REPLENISHING MECHANISM (Pirn changing):-
Weft replenishing mechanism (pirn changing) :-
There are various types of weft replenishing motion , here I am going to discussed about the two main motion ,1) Pirn changing motion.
2) Shuttle changing motion.
(1) Pirn changing motion:-
The following parts or attachments are found essential for operating this mechanism.
1. A large shuttle and pirn with few changes in design.
2. Changes in the design of the shuttle boxes and slay.
3. A rotary magazine to accommodate 24 to 32 fully wound pirn.
4. A feeler mechanism on the starting handle side to detect the almost exhausted pirn or weft break for any reason.
5. A mechanism to push the fully wound pirn from the magazine into shuttle and at the sometime eject the empty pirn.
6. A self threading device in the shuttle.
7. A device to cut the two end of weft at the selvedge of the cloth and at the pirn changing side.
8. Among the two weft end , on which from the out going almost empty pirn and the other form a new fully wound pirn is going pirn
8. A mechanism known as shuttle protecter, to prevent changing mechanism from fraying to insert a new fully wound pirn in the shuttle should the shuttle fail to exactly in the correct portion for receiving the bobbin.
MECHNISM:-
The change shaft which runs across the width of the breast beams partially rotated so as to impart an upward movement to the shuttle protecter lever A which contacts the peg B and give a forward throw to the shuttle protector C. The latch dresser D which moves along the protecter C release, it holds on the depressor and pressure from the latch spring F and ultimately always the latch G to swing upward S into line with the bunter H which is fixed in the slay front. Under normal running conditions the spring loaded transfer latch G is held in the depressed position by means of a peg E which resist against the latch dresser D.
As the slay moves forward for beating-up of weft and the shuttle having reached the battery end the bunter H engages the notch on the latch G forcing it backward against the resistance of hammer I fulcrummed on the stud J together with the transfer depressor K . During the downward movement, the hammer and the depressor K imparts a sharp blow to the fully wound pirn that is immediately underneath held by the battery.
Where a full pirn is forced into shuttle it expels the almost exhausted (empty) pirn out of the shuttle, making it pass through the slots provided in the bottom of the shuttle and shuttle box, and fall into the container. The new pirn which is forced into the shuttle is firmly held in the spring jaws of the shuttle .
Connected to the transfer hammer I is the feed pawl L , the catch of which rests in one of the ratchet wheel wheel M . As the hammer is depressed for transfer of the new pirn into the shuttle, it lowers the feed pawl L. So that the catch slip into next tooth ratchet wheel. As soon as the transfer of the pirns take place , the receding slay breaks the contact between the bunter and the latch and enables the hammer to move up to its original position due to the pressure of the hammer coil spring S and doing it pushes the feed pawl L upward aided by a spring underneath the pawl , and turns the ratchet wheel in one tooth bringing the next full pirn in the battery right below the hammer for the subsequent transfer.
(2) Shuttle changing mechanism:-
The shuttle changing automatic looms are suitable for weaving very delicate weft like silk ,rayon and fine count of cotton yarn because there is no hammer action on the weft package . As soon as weft get exhausted on the pirn the entire shuttle replaced by a new shuttle with fully wound pirn.
There are two main types of shuttle changing looms, they are;
1. One which does not stop for change or in which change is affected during the running of the loom .
2. One which stop the loom for few seconds for change and restart automatically.
Ref:-https://fabricclub.blogspot.com
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